1. Field of the Invention
The present invention relates to a UV (ultraviolet)/fluorescence detecting apparatus and sensing method thereof capable of determining a paper sheet quality and so on by projecting ultraviolet ray to a paper or the like and detecting fluorescence excited and ultraviolet ray reflected thereby.
2. Description of the Related Art
Conventionally, there is an apparatus for detecting the quality of a paper sheet by projecting ultraviolet ray to that paper sheet and receiving fluorescence excited and the ultraviolet ray reflected thereby. The structure of such an apparatus employing the ultraviolet ray comprises a UV lamp composed of a cold cathode, an inverter power supply for driving the UV lamp, a photo diode for detecting excited and emitted fluorescent material, a photo diode for monitoring the amount of light from the light source, an optical filter and a photo diode processing circuit (I-V converting circuit).
For example, Japanese Patent Application Laid-open No. 6-309546 A has already disclosed an apparatus having a detecting function for fluorescent material contained in foreign bills and so on. The apparatus described in this publication utilizes a single square rod shaped glass block 21 shown in FIG. 1 as its optical system and its incident face 21a and reflection/emission face 21b are provided with a filter function, thereby reducing the size of the apparatus and facilitating positioning of the optical system. In the example of FIG. 1, the incident face 21a is provided with a film having a filter function which shields visible light component of excited light while permitting only ultraviolet ray region to pass through, this film being formed by vapor deposition or the like. Then, the reflection/emission face 21b is provided with a film having a filter function which reflects the excited light while allowing fluorescence generated from a fluorescent material of a detection object xe2x80x9caxe2x80x9d to pass through, this film being formed by the vapor deposition or the like. Then, the excited light from the light source 22 is projected onto the detection object xe2x80x9caxe2x80x9d like a bill through the detection face 21c by using for example, a UV lamp as the light source 22 and its reflectted light is received by a detector 23 through a reflection/emission face 21b so as to detect a fluorescent material.
For example, Japanese Patent Application Laid-open No. 8-185558 A has disclosed an apparatus having a detecting function for both fluorescence and reflected ultraviolet ray. In the apparatus described in the above publication, as shown in FIG. 2, ultraviolet ray from the UV lamp 32 is irradiated on the detection object xe2x80x9caxe2x80x9d through the window 31 having ultraviolet ray transmissibility and its reflected light is received so as to detect fluorescence and reflected ultraviolet ray with the detector 33. The detector 33 mounted on a printed circuit board 34 is comprised of a sensor for detecting ultraviolet ray and a sensor for detecting fluorescence each composed of a photo diode and the like, a filter for ultraviolet transmission, a visible light transmitting filter, a micro controller and the like. Then, according to this system, a document such as marketable securities and so on is certified based on both the characteristic relating to reflected ultraviolet ray and characteristic about generation of fluorescence.
Because in the above-described conventional example, a cold cathode is utilized as a light emission body of the UV lamp, a small sensor suitable for a spot is difficult to make. If the cold cathode is used, a predetermined amount of light is not obtained just when power is turned on, but brightness increases as the temperature increases. Therefore, it is necessary to carry out correction with a passage of time. Further, if it is always turned on, it needs to be replaced at a short time (about a thousand hours) interval because its service life is short. Further, because an inverter is required to drive the cold cathode and the inverter acts as a noise source, it is difficult to detect a weak fluorescent pattern.
The present invention has been achieved in views of the above described problems and therefore, an object of the present invention is to provide a UV/fluorescence detecting apparatus which is capable of detecting both a fluorescent pattern and ultraviolet reflected light, and small and cheap, and a sensing method thereof. Further, another object of the present invention is to provide a UV/fluorescence detecting apparatus capable of detecting a fluorescence of a specific color and a sensing method thereof.
The present invention relates to a UV/fluorescence detecting apparatus and a sensing method capable of examining the quality of a paper or the like by projecting ultraviolet ray on the paper and detecting an excited fluorescence and a reflected ultraviolet ray. The above object relating to the invention of the UV/fluorescence detecting apparatus is achieved by provision of a sensor unit comprising: a light source portion including an ultraviolet ray LED for emitting ultraviolet ray through an opening window portion and an ultraviolet ray monitor provided beside the ultraviolet ray LED; a light detector receiving portion disposed in a chamber partitioned with a partition plate for receiving an incident light impinging through the opening window portion; the partition plate for partitioning between the light source portion and the light detector receiving portion; a transparent body provided on the both opening window portions; a first filter provided in a window portion on projection side of the ultraviolet ray for allowing a ultraviolet ray region to pass through; and a second filter provided in a window portion on light receiving side of the incident light for allowing a visible light region to pass through.
Further, each of the invention is more effectively achieved by the following:
The ultraviolet ray monitor is disposed at a position where it receives both a direct light of the ultraviolet ray and a ultraviolet ray reflected by an object for detecting a light emission amount of the ultraviolet ray and a ultraviolet ray reflected by the object. The detected light receiving portion detects a light of wavelength determined to pass through by said second filter. A blue filter is attached to the window portion on the light projection side as the first filter while a red filter is attached to the window portion on the light receiving side as the second filter. The second filter is provided so as to be replaceable with a filter of the color corresponding to light of color which should be detected.
As regards of the UV/fluorescence detecting apparatus and the sensing method, the above object is achieved by a sensing method of the UV/fluorescence detecting apparatus comprising a light source portion including an ultraviolet ray LED for emitting ultraviolet ray through a window portion and an ultraviolet ray monitor provided beside the ultraviolet ray LED at a position for receiving both a direct light of the ultraviolet ray and an ultraviolet ray reflected by the surface of a paper sheet and a light receiving sensor for receiving incident light impinging through a window portion of a chamber partitioned with a partition plate from the light source portion, the sensing method comprising: a step for setting the emitted amount of an initial UV light using the ultraviolet ray monitor; a step for reading and memorizing a set value at a waiting time read by the ultraviolet ray monitor; a step for moving a unit having the sensing portion relative to the surface of a paper sheet; a step for sampling visible light with the light receiving sensor; a step for sampling ultraviolet ray with a sensor in the ultraviolet ray monitor; and a step for processing as an ultraviolet ray reflected by the surface of the paper sheet by subtracting the set value at the waiting time from the sample value of the ultraviolet ray.